In book 22 of the Odyssey, why does Homer include epithets in the narrative, and what is the effect? Why does he use epithets so generously with the virtuous characters and so sparingly with the wrongdoers: I need a thesis state that makes a contention about WHY and HOW Homer uses these epithets and the effect on the narrative of his doing so. I need to write two topic sentences that clearly and directly support my thesis.

In order to answer this question, we should first consider what epithets are and why Homer uses them at all. Remember that the poems we know as the Odyssey and the Iliad would have once been stories transmitted orally about characters everybody would have recognized and understood. The use of an epithet not only helps the singer or poet remember the verses, the epithet also is a cue to the audience as to what character is being referred to—and what, according to the poet, is the defining feature or characteristic of that person at this particular point in time. So, just as on a modern television drama we might have a recap before the story resumes, the epithets in the Homeric epics often serve to remind us of how far a character has come and how the poet sees them. For gods and goddesses, we frequently see the same epithets that reflect a certain timelessness—"grey-eyed Athena"—but for Odysseus and other characters, the epithets do evolve.
Epithets, far more often than not, are flattering descriptors; while an epithet is not in and of itself necessarily positive, in the works of Homer, we do see epithets applied far more liberally to virtuous characters than to wrongdoers. In book 22 of the Odyssey, for example, we are told of "Odysseus of many wiles" before Odysseus embarks upon his plan. The epithet then serves the purpose of reminding the audience why the plot makes sense: because of this particular characteristic of our hero, he is able to perform these feats. This epithet is repeated several times, reinforcing the point: Odysseus is able to do what he is doing because of this particular positive feature. The epithet underlines why Odysseus is justifiably the hero, rather than the villain, of his own story. In this book, Odysseus is also "goodly" and "glorious," descriptors which afford him virtue as well as cleverness.
We could argue further for this element of plot advancement in the epithets if we look at how Melanthius is repeatedly described as "the goatherd," a descriptor which simply helps the audience to understand why he should be there amidst the events that are taking place.
A thesis statement built upon this evidence, then, might read something like this:
"Homer uses epithets in the Odyssey in order to remind the audience of what particular qualities his characters possess and how these contribute to the forward motion of the plot. He uses epithets to describe his virtuous characters both to underline and justify their presence as heroes of the story. The repeated epithets serve to lend cohesion to the narrative and to remind the audience of each character's role within it."